430. Acanthopneuste davisoni.
The Tenasserim White-tailed Willow- Warbler.
Reguloides viridipennis (? Blyth), apud Wald. in Blyth Birds Burm. p. 106. Reguloides viridipennis (Blyth), apud Hume, S. F. v, p. 330 ; Hume & Dav. S. F. vi, p. 358; Hume, Cat. no. 567; id. S. F. vii, p. 453, ix, p. 291, xi, p. 223. Phylloscopus viridipennis, Blyth, apud Seebohm, Cat. B. M. v, p. 53. Phylloscopus presbytis (S. Mull.), apud Oates, B. B. i, p. 86; Brooks, Ibis, 1889, p. 576. Acanthopneuste davisoni, Oates; Oates in Hume's N. & E. 2nd ed. i, p. 269.
Coloration. Very similar to A. trochiloides, but differing in being smaller and in having the inner webs of the two outside tail-feathers white.
Legs and feet rather pale brown; soles yellowish ; upper mandible dark brown; lower wax-yellow; iris brown (Hume).
Length about 4.3; tail 1.7; wing 2.1 ; tarsus .75; bill from gape .55; the second primary is about equal to the tenth; the first primary is about -55 inch long.
After a careful reconsideration of the synonymy of this species I am reluctantly compelled to give it a name and I have much pleasure in naming it after Davison, its discoverer.
The history of the species is briefly this. In 1855 Blyth described a Willow-Warbler from Tenasserim under the name of Phylloscopus viridipennis. He neglected to state what the colour of the tail was ; an all-important matter. Davison, many years after, procured a white-tailed Willow-Warbler in Tenasserim, and Hume unhesitatingly identified it with P. viridipennis, Blyth. Against this, we have Brooks's positive evidence that he examined Blyth's types in Calcutta and found them to be the bird we know as A. trochiloides. The opinion of Brooks on such a subject is in my opinion conclusive. We also have Jerdon describing P. viridipennis, Blyth, in the ' Birds of India,' as having an olive-green tail, no mention being made of any white feathers, and he states that it occurs at Darjiling. This locality coupled with the description point to A. trochiloides; for the Tenasserim white-tailed bird is not known to occur in Sikhim.
It must be borne in mind that Blyth's P. viridipennis is just as likely to have been A. trochiloides as the present species discovered by Davison, for both species were found by Davison in Tenasserim, the former in the Salween district, the latter on Muleyit mountain, no great distance apart. For all these reasons therefore I reject Blyth's name as inadmissible for the present form.
In 1870 Blyth visited the Leyden Museum and there observed a white-tailed Willow-Warbler which Muller in 1835 had named presbytis without a description. Leaving alone such a minor complication as that of this bird being labelled " Timor," while Muller's bird came from Sumatra, it is to be noticed that this white-tailed Acanthopneuste did not recall to Blyth any recollection of his Tenasserim bird. He describes Muller's bird as something distinctly new. I require no better evidence than this to convince me that Blyth had never described a white-tailed Acanthopneuste of this type before. He would, of course, not associate it with his Abrornis maculipennis, which is a totally different bird, and one to which no special reference was necessary; but it was to be expected that he would mention his Phylloscopus viridipennis, if it had been a white-tailed species, as one closely allied to A. presbytis.
This A. presbytis, judging from specimens in the British Museum collected by Wallace in Timor, is not by any means identical with the bird procured by Davison on Muleyit, having a browner head and a much larger bill, and I should not have noticed it in this work had not Seebohm united it with Phylloscopus viridipennis, Blyth, apud Hume. I did not inquire very minutely info the matter when writing the ' Birds of Burmah,' but I have now devoted considerable time to the subject, and I think it far from established that the Timor bird described by Blyth is identical with the Tenasserim white-tailed Willow-Warbler. Looking to this and to the very unsatisfactory history of the synonymy of this species, I prefer to denote it by a new name.
Distribution. Discovered on Muleyit mountain in Tenasserim, where it breeds and appears to be a permanent resident. I have examined two specimens procured by Wardlaw Ramsay on the Karen Hills and Karennee respectively, and Hume procured this species in Manipur above Bishnupur on the 17th February, at an elevation of about 3300 feet.
Habits, &c. Davison found the nest of this species on Muleyit, at an elevation of over 6000 feet, placed in a mass of creepers growing over the face of a rock. The nest was a globular structure constructed of moss and leaves and lined with vegetable down. It contained three pure white eggs which measured .59 by .49.